Methodology

• Ground Penetrating Radar (GPR) Measurements

  A GPR system was hired from Auckland University and GroundSearch Ltd. We employed three different antennae (35, 200 and 400 MHz). The 35 MHz antenna pair was used in differential mode, so absolute depths of the glacier could be calculated. The system was deployed on a Nansen sledge towed and secured by two skidoos, allowing a vast area of the glacier to be investigated.

• Differential Global Positioning System (GPS) Measurements

  The GPS system Trimble 4000 SSE performed well, with the base station installed on the southern glacier margin. The GPS system was used for our GPR and mass balance measurements.

  

  Fig.6: GPS base station

• Snow Profiling and Sampling

  Four snow profiles (5, 1, 4 and 3m) were described and sampled. After a detailed description of the physical features, the pits were sampled in 1cm resolution for isotopic ratios and major ion content. In order to avoid contamination of the chemistry samples, clean suits and high density polyethylene gloves were used. All sampling tools have been regularly cleaned with methanol. Dust and beta activity samples were taken with 5cm spacing. While the dust could be filtered in the field, the radioactivity samples had to be transported back to NZ. Density and temperature values were measured on site.

• Ice Core Drilling

  For the ice core drilling the PICO (Polar Ice Coring Office) hand auger with power head was used. The system was received in poor condition, and drilling hard ice was not possible. However Scott Base supplied numerous spare parts, wherefore the drilling performance was improved and firn cores were recovered.

• Borehole Temperature Measurement

  Coupled conductivity wire were used to read the temperature profile. The meter displayed a high sensitivity to the ambient air temperature and had to be kept above 0°C.

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• Meteorological Measurements

  A climate station was installed at Victoria Lower Glacier for eight weeks. The record included air temperature, relative humidity, wind speed and direction, air pressure, and snow pack temperature.

• Current Dust and Diatom Flux

  In order to measure current dust and diatom flux on Victoria Lower Glacier two traps were deployed in the proximity of the VLG camp (VIC 1). The containers in the traps were collected and replaced every three days.

• Current Ablations Measurements

  15 Ablation stakes were placed at VLG in the vicinity of the climate station. The relative change of snow depth was measured weekly or after individual snowfall events.